Session: Thursday Afternoon, June 19

Time: 4:10

A small population of about 500 beluga whales, Delphinapterus leucas,
resides in the Saint Lawrence estuary, isolated from other populations of its
species. This population has been extensively studied over the last 12 years in
terms of its seasonal distribution, size, age, group structure, pathology, and
group behavior. It is now considered to be threatened by human activities
including elevated noise levels due to a wide range of anthropogenic sources
including merchant shipping and whale watching activities. A whale recovery plan
is in development that will include hearing conservation. Ambient noise
measurements mwere made at the three major sites of habitation of these whales
to gain an understanding of the daily fluctuations in noise levels and to
establish a baseline characterization of the acoustic environment at each site.
The noise levels were related statistically by site, time of day, and human
activity and compared to beluga hearing sensitivity curves [W. Au, The Sonar of
Dolphins (1993)] and indicate the probability that hearing damage will occur for
animals occupying two of the three sites. Specifically, 200 Hz, 500 Hz, and 1
kHz and 40 kHz were scrutinized. [Work supported by World Wildlife Fund Canada,
Humane Society Canada, and Parks Canada.]